It sounds like you have been feeding your bird the wrong kind of
birdseed.  There are two bird box doctors that I know of, Ray Lins
and Moe Goldy.  But I think Ray Lins has retired from practice.

Moe Goldy, Port St. Lucie, Fla. is still in business for sure.
Contact him at <mgoldy@earthlink.net>

You could try Ray, who is in Burnsville, Minn., with an email to
<r.lins@att.net>

Matthew Caulfield
Irondequoit, New York